import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import com.gq.utils.Base64;

public class MCrypt {

	private String iv = "fedcba9876543210";//Dummy iv (CHANGE IT!)
	private IvParameterSpec ivspec;
	private SecretKeySpec keyspec;
	private Cipher cipher;
	public static final int BLOCK_SIZE = 32;
	
	private String SecretKey = "longhoanggiang";//Dummy secretKey (CHANGE IT!)
	
	public MCrypt()
	{
		ivspec = new IvParameterSpec(iv.getBytes());

		keyspec = new SecretKeySpec(padString(SecretKey).getBytes(), "AES");
		
		try {
			cipher = Cipher.getInstance("AES/CBC/NoPadding");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		}
	}
	
	public byte[] encrypt(String text) throws Exception
	{
		if(text == null || text.length() == 0)
			throw new Exception("Empty string");
		
		byte[] encrypted = null;

		try {
			cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
			encrypted = cipher.doFinal(padString(text).getBytes());
		} catch (Exception e)
		{			
			throw new Exception("[encrypt] " + e.getMessage());
		}
		
		return encrypted;
	}
	
	public byte[] decrypt(String code) throws Exception
	{
		if(code == null || code.length() == 0)
			throw new Exception("Empty string");
		
		byte[] decrypted = null;

		try {
			cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
			decrypted = cipher.doFinal(Base64.decode(code, Base64.DEFAULT));
		} catch (Exception e)
		{
			throw new Exception("[decrypt] " + e.getMessage());
		}
		return decrypted;
	}
	
	public String decrypt2(String code) throws Exception
	{
		if(code == null || code.length() == 0)
			throw new Exception("Empty string");
		
		byte[] decrypted = null;

		try {
			byte[] cipherByte = Base64.decode(code, Base64.DEFAULT);
			
			byte[] ivByte = new byte[16];
			for (int i=0;i<16;i++) {
				ivByte[i] = cipherByte[i];
			}
			byte[] contentByte = new byte[cipherByte.length - ivByte.length];
			int j = 0;
			for (int i=0;i<contentByte.length;i++) {
				j = i + 16;
				contentByte[i] = cipherByte[j];
			}
			ivspec = new IvParameterSpec(ivByte);
			cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
			decrypted = cipher.doFinal(contentByte);
		} catch (Exception e)
		{
			throw new Exception("[decrypt] " + e.getMessage());
		}
		return unpaddString(new String(decrypted));
	}

	
	public static String bytesToHex(byte[] data)
	{
		if (data==null)
		{
			return null;
		}
		
		int len = data.length;
		String str = "";
		for (int i=0; i<len; i++) {
			if ((data[i]&0xFF)<16)
				str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);
			else
				str = str + java.lang.Integer.toHexString(data[i]&0xFF);
		}
		return str;
	}
	
		
	public static byte[] hexToBytes(String str) {
		if (str==null) {
			return null;
		} else if (str.length() < 2) {
			return null;
		} else {
			int len = str.length() / 2;
			byte[] buffer = new byte[len];
			for (int i=0; i<len; i++) {
				buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
			}
			return buffer;
		}
	}
	
	private static String unpaddString(String inputStr) {
		int strLen = inputStr.length() - (int) inputStr.charAt(inputStr.length() - 1);
		return inputStr.substring(0, strLen);
	}

	private static String padString(String inputStr)
	{
//	  char paddingChar = '\000';
	  int padLength = BLOCK_SIZE - inputStr.length() % BLOCK_SIZE;
	  char paddingChar = (char) padLength;
	  for (int i = 0; i < padLength; i++)
	  {
		  inputStr += paddingChar;
	  }
	  return inputStr;
	}
}